CVE-2020-6798Public exploitNetwork attack vector

Cross-site scripting via incorrect parser-state reset

Published Mar 2, 2020 · Updated Aug 4, 2024

Cross-site scripting in Mozilla Firefox before 73 or ESR 68.5 and Thunderbird before 68.5 allows remote attackers to execute JavaScript. The innerHTML path resets the HTML parser insertion mode after a closing template element and forgets that parsing remains inside select. Exploitation requires attacker-controlled markup to reach innerHTML; normal Thunderbird mail reading disables scripting, limiting exposure to browser-like contexts.

CVSS severity6.1
Medium
EPSS probability2.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in Mozilla Firefox before 73 or ESR 68.5 and Thunderbird before 68.5 allows remote attackers to execute JavaScript. The innerHTML path resets the HTML parser insertion mode after a closing template element and forgets that parsing remains inside select. Exploitation requires attacker-controlled markup to reach innerHTML; normal Thunderbird mail reading disables scripting, limiting exposure to browser-like contexts.

The record

CVE
CVE-2020-6798
Published
Mar 2, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 2, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <73
  2. Affected versionversion=unspecified <ESR68.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <73; version=unspecified <ESR68.5
Mozilla · Thunderbirdversion=unspecified <68.5

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo